Web Services forDigital Library Construction

T. Hickey

Indo-US Workshop

June 2003

What are Web Services?

• Machine-to-machine communication• Run over standard Web protocols

– XML syntax, HTTP packaging

• Several approaches– REST

• Representational State Transfer

– SOAP• Simple Object Access Protocol

REST

• REST is simplest– Send an HTTP request– Get back a response (XML, HTML)– Examples

• Web browser• OpenURL• Z39.50 as a Web service: SRU

http://sfx.bath.ac.uk/sfxmenu?genre=book&isbn=1234-5678

http://www.kb.nl/cgi-zoek/srw.pl?query=test&maxRec=10&recSchema=dc_record

SOAP is more complex

• Simple Object Access Protocol

• Z39.50 as a SOAP service: SRW– http://www.loc.gov/z3950/agency/zing/srwu/wsdl/zing_srw_binding.wsdl

• WSDL

• UDDI

A set of Web services for the digital library

• Register• Search• Resolve• Navigate• Decompose• Enhance• Transform

Skip to examples

Registration Services

• Metadata about metadata– Dublin Core extensions– Digital format descriptions

• Metadata about objects– Books– Web resources

• Metadata about agents– People– Institutions

Search Services

• Go from data to links– Name to preferred form– Search terms to record list

Resolution Services

• From links to data– Record numbers to records– Controlled names to name metadata– Class number to textual description

Navigation Services

• Movement within hierarchies– Classification, e.g. DDC– FRBR (work, expression, manifestation, item)

• General network movement– Link selection and following

Decomposition Services

• DDC Numbers

• Names within a list

• Citations within a paper

• Structure of a document

• Letters within an image

Enhancement Services

• Normalization– Linkage to registered forms

• Addition of DDC numbers

• Authority control on agents

• Content augmentation– Add information to a brief record from a

matching longer record

Transformation Services

• Syntax translation– MARC21 to MARC XML

• Semantic translation– Qualified Dublin Core to MARC21– Library of Congress SH to FAST

• Content translation– English to French?

Examples of Web Services

• XISBN service– Maps ISBNs to ISBNs

• OpenURL Registry– Provides names and definitions for OpenURL

services

• GSAFD Thesaurus

The XISBN Web Service

User

Amazon

Library

FRBRizedISBN Server

On Amazon

Cornell University

OpenURL Registry

• OAI-PMH Registry– http://purl.org/openurl/ – OAI implies XML delivered

• But, stylesheets can produce– HTML display– Web browser user interface

GSAFD as a test case

• Enhanced subject authority records for genre terms are now available via the OAICat framework. This development is a result of the combined efforts of the OAICat project and the Terminology Services project. The enhanced authority file is a version of the MARC 21 authority records for GSAFD genre terms. The enhanced version of the file has the following features:

– The content of the file is MARC XML

– Established terms in the file are accessible via a URL

– Established terms in the file are mapped to equivalent Library of Congress Subject Headings (lcsh) and Library of Congress subject headings: Annotated Card Program (lcshac) (i.e., LC Children’s heading)

– Authority records can be displayed in MARC or in a thesaurus-style display

– The file is also accessible via SRW/SRU under the Zthes protocol